Description

GtkScrolledWindow is a GtkBin subclass: it's a container
the accepts a single child widget. GtkScrolledWindow adds scrollbars
to the child widget and optionally draws a beveled frame around the
child widget.

The scrolled window can work in two ways. Some widgets have native
scrolling support; these widgets have "slots" for GtkAdjustment
objects.
[5]
Widgets with native scroll support include GtkTreeView, GtkTextView,
and GtkLayout.

For widgets that lack native scrolling support, the GtkViewport
widget acts as an adaptor class, implementing scrollability for child
widgets that lack their own scrolling capabilities. Use GtkViewport
to scroll child widgets such as GtkTable, GtkBox, and so on.

The position of the scrollbars is controlled by the scroll
adjustments. See GtkAdjustment for the fields in an adjustment - for
GtkScrollbar, used by GtkScrolledWindow, the "value" field
represents the position of the scrollbar, which must be between the
"lower" field and "upper - page_size." The "page_size" field
represents the size of the visible scrollable area. The
"step_increment" and "page_increment" fields are used when the user
asks to step down (using the small stepper arrows) or page down (using
for example the PageDown key).

If a GtkScrolledWindow doesn't behave quite as you would like, or
doesn't have exactly the right layout, it's very possible to set up
your own scrolling with GtkScrollbar and for example a GtkTable.

Details

GtkScrolledWindow

typedef struct _GtkScrolledWindow GtkScrolledWindow;

There are no public fields in the GtkScrolledWindow struct; it should
only be accessed using the functions below.

gtk_scrolled_window_new ()

Creates a new scrolled window. The two arguments are the scrolled
window's adjustments; these will be shared with the scrollbars and the
child widget to keep the bars in sync with the child. Usually you want
to pass NULL for the adjustments, which will cause the scrolled window
to create them for you.

gtk_scrolled_window_set_policy ()

Sets the scrollbar policy for the horizontal and vertical scrollbars.
The policy determines when the scrollbar should appear; it is a value
from the GtkPolicyType enumeration. If GTK_POLICY_ALWAYS, the
scrollbar is always present; if GTK_POLICY_NEVER, the scrollbar is
never present; if GTK_POLICY_AUTOMATIC, the scrollbar is present only
if needed (that is, if the slider part of the bar would be smaller
than the trough - the display is larger than the page size).

gtk_scrolled_window_add_with_viewport ()

Used to add children without native scrolling capabilities. This is
simply a convenience function; it is equivalent to adding the
unscrollable child to a viewport, then adding the viewport to the
scrolled window. If a child has native scrolling, use
gtk_container_add() instead of this function.

The viewport scrolls the child by moving its GdkWindow, and takes the
size of the child to be the size of its toplevel GdkWindow. This will
be very wrong for most widgets that support native scrolling; for
example, if you add a widget such as GtkTreeView with a viewport, the
whole widget will scroll, including the column headings. Thus, widgets
with native scrolling support should not be used with the GtkViewport proxy.

A widget supports scrolling natively if the
set_scroll_adjustments_signal field in GtkWidgetClass is non-zero,
i.e. has been filled in with a valid signal identifier.

gtk_scrolled_window_set_placement ()

Determines the location of the child widget with respect to the
scrollbars. The default is GTK_CORNER_TOP_LEFT, meaning the child is
in the top left, with the scrollbars underneath and to the right.
Other values in GtkCornerType are GTK_CORNER_TOP_RIGHT,
GTK_CORNER_BOTTOM_LEFT, and GTK_CORNER_BOTTOM_RIGHT.

See Also

[5] The scrolled window installs GtkAdjustment objects in
the child window's slots using the set_scroll_adjustments_signal,
found in GtkWidgetClass. (Conceptually, these widgets implement a
"Scrollable" interface; because GTK+ 1.2 lacked interface support in
the object system, this interface is hackily implemented as a signal
in GtkWidgetClass. The GTK+ 2.0 object system would allow a clean
implementation, but it wasn't worth breaking the
API.)